阅读下表，表中各大国钢铁产量在不同阶段发生变化的主要原因是（    ）

1938年各大国的钢铁产量（单位：百万吨）

——摘编自（英）保罗·肯尼迪著《大国的兴衰》

小说写德拉和吉姆夫妇的爱情悲喜剧，却以“麦琪的礼物”为题的原因是什么？

     I think the best place to go on Sunday is the zoo. When you are 1, you can go there with your family. 2the zoo, there are many animals: elephants, deer,3, rabbits and other animals. Elephants are the 4 animals on land. I 5there is a baby elephant in our zoo. So I want to6at it. Yu Xuan wants to go with me. She says, " 7we go there together?" "Sure!" I say. "We can 8 a good time there. But let's 9 there at half past four. I have 10 homework to do."

已知2x^my³与3xyⁿ是同类项，则代数式m－2n的值是（  ）